add option to avoid "sharp" turns when routing

[zoff99]

you can see that there would be a very sharp left turn. almost a u-turn. not all those can be avoided by adding a turnrestriction to the osm data. so maybe we should introduce a feature that the routing engine should not allow turns with more than 91° angle (left or right) to avoid routes like this one. and also sometimes navit suggests a u-turn on the "autobahn", which is not good

see the route here: ​http://map.project-osrm.org/187

[zoff99]

route with sharp turn

[korrosa]

Is that an illegal turn (the one in the screenshot)? If not, then I'm not sure there is an issue here. The fastest route to your final destination is shown, because of a couple of turn restrictions on the more obvious routes. Granted, it's not the prettiest. If there are occasions where such a turn is illegal, then yes, the data must be updated with turn restrictions: we can't just have Navit blindly assuming that all >90deg turns are naughty.

However, U-turn on an autobahn sounds like a bad error. I presume this is illegal? Can you provide a location example?

[usul]

I expect this issue in the context of trucks, HGVs and busses that need a lot of space to turn?

Please give of some more informations on your scenario.

Currently this doesn't seem to be a real bug, as I can't see that this is an illegal routing, too. So I will schedule it just for the next major release.